Gluten is formed when water is added to flour and stirred, mixed, beaten or kneaded. The dough's gluten network traps the air beaten into the recipe, which expands from the carbon dioxide that's produced by the added yeast, baking soda or baking powder, allowing the dough or batter to rise. During baking, the gluten network stretches like a net to contain the expanding air bubbles during rising. At a certain point in baking, the stretched flour proteins become set, resulting in the structure of the baking recipe, Margles said.
The different wheat flour types contain varying amounts of the gluten-forming proteins, which determine its use in a recipe. If too much gluten is produced, caused by either the protein percentage in the flour or too much handling, it gives toughness to a recipe, Margles said.
Types of flour
Professional bakers choose flours formulated for specific purposes because they give the best results, Margles said. They generally avoid using all-purpose flour, which is made from a blend of hard and soft wheat flours and is weaker than bread flour.
"All-purpose flour, as far as I'm concerned, is like one-size-fits-all pantyhose. It doesn't fit anybody very well," Stoliar said. She said the percentage of protein in all-purpose flours varies from region to region and season to season. "It is milled differently for different parts of the United States."
Stoliar and Margles said better flour choices include:
· Cake flour, which contains 6 percent to 8 percent protein and is made from soft wheat flour. It is chlorinated to further break down the strength of the gluten and is smooth and velvety in texture. Cake flour is ideal for making biscuits, cakes - especially white cakes - and cookies when a tender and delicate texture is desired. Cake flour must be sifted at least twice before baking to aerate it, Stoliar said. To substitute cake flour for all-purpose flour, use 1 cup plus 2 tablespoons cake flour for every cup of all-purpose flour. You also can make your own cake flour, Margles said. For one cup sifted cake flour, mix 3/4 cup sifted bleached all-purpose flour and 2 tablespoons cornstarch.
· Pastry flour, which is ideal for making pastry, pies and cookies. It also is made from soft wheat flour, but it contains 8 percent to 10 percent protein. Pastry flour - which might be difficult to find in grocery stories but can be ordered online and sometimes purchased at local bakeries - makes the best pie crusts and cookies, Stoliar said. Pastry flour absorbs fats and repels liquids, so pastry-flour pie crusts won't come out of the oven soggy like crusts made from all-purpose flour often do, she said. To make two cups of pastry flour, combine 1 1/3 cups all-purpose flour with 2/3 cup cake flour, Margles said.
· Bread flour, which is made from hard wheat flour and contains 12 percent to 14 percent protein. It is ideal for making bread and some pastries because the high gluten content causes the bread to rise and gives it shape and structure, Margles said. Strong bread flours can produce thin, tender crusts; and medium bread flours are best for artisan-type breads with crusty loaves, Stoliar added.
Self-rising flour has 8 percent to 9 percent protein and contains baking powder and salt. Margles shies away from using self-rising flour because the baking powder can lose some of its strength if stored for too long. To make self-rising flour, add 1 1/2 teaspoons baking powder and 1/2 teaspoon salt per cup of all-purpose flour.